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— CH. 1 · DISCOVERY AND NAMING HISTORY —

25143 Itokawa

~3 min read · Ch. 1 of 6
6 sections

  • Astronomers with the Lincoln Near-Earth Asteroid Research program spotted a faint point of light on the 26th of September 1998. The observation occurred at Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico. This object received the provisional designation 1998 MO11 during that initial sighting. An earlier observation by the Sloan Digital Sky Survey had captured the same body just one week before this official discovery. The Minor Planet Center officially published the name Itokawa on the 6th of August 2003. They chose to honor Japanese rocket scientist Hideo Itokawa who lived from 1912 to 1999. He is widely regarded as the father of Japanese rocketry.

  • Itokawa belongs to the Apollo group of asteroids which cross Earths orbit. There are nearly 10,000 known members in this largest dynamical group of near-Earth objects. The asteroid orbits the Sun at a distance ranging from 0.95 to 1.70 AU every 18 months. Its orbital period lasts exactly 557 days with a semi-major axis of 1.32 AU. The path has an eccentricity of 0.28 and an inclination of 2 degrees relative to the ecliptic. A low Earth minimum orbital intersection distance corresponds to 5.1 lunar distances. These parameters classify it as a potentially hazardous asteroid due to its proximity to our planet.

  • Japan selected Itokawa as the target for their Hayabusa mission in 2000. The probe arrived in the vicinity of the asteroid on the 12th of September 2005. It initially parked along an asteroid-sun line before adjusting its solar orbit to match the weak gravity field. On the 20th of November 2005 the spacecraft attempted a landing that lasted thirty minutes but failed to operate its soil collection device. A second landing sequence was attempted on the 25th of November 2005. The sample capsule returned to Earth and landed at Woomera, South Australia on the 13th of June 2010 around 13:51 UTC. Japan Aerospace Exploration Agency confirmed dust from the voyage originated from the asteroid on the 16th of November 2010.

  • Radar imaging by Goldstone in 2001 observed an ellipsoid shape measuring approximately 540 meters long and 290 meters wide. Hayabusa images revealed a surprising lack of impact craters and a very rough surface studded with boulders. The density of the asteroid is too low for it to be made from solid rock. This means Itokawa is not a monolith but rather a rubble pile formed from fragments that have cohered over time. Scientists suggest it may be a contact binary formed by two or more smaller asteroids that gravitated toward each other. One section has an estimated density of 1.8 g/cm3 while another small section shows different values based on Yarkovsky measurements.

  • The 26th of August 2011 issue of Science devoted six articles to findings based on dust collected from Itokawa. Dust particles were thought to have been exposed at the surface for about eight million years. Analysis showed composition matching common meteorites known as low-total-iron ordinary chondrites. Another team determined dark iron color resulted from abrasion by micrometeoroids and high-speed solar particles. These interactions converted normally whitish iron oxide coloring into darker shades. Scientists used varied techniques of chemistry and mineralogy to analyze the returned samples in detail.

  • Two separate groups reported water presence in different Itokawa particles during later studies. Jin et al found water in low-calcium pyroxene grains with isotope levels corresponding to inner Solar System sources. Daly et al reported hydroxide and water molecules apparently formed by implantation of solar wind hydrogen. The rims of olivine particles show enrichment up to approximately 1.2 atomic percent in OH and H2O. Smooth deposits of dust accumulate in depressions like craters contrasting from rocky terrain around them. These features called dust ponds appear in Sagamihara and Muses-Sea regions with particle sizes varying from millimeters to less than a centimeter.

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When was the asteroid 25143 Itokawa discovered?

Astronomers with the Lincoln Near-Earth Asteroid Research program spotted 25143 Itokawa on the 26th of September 1998. An earlier observation by the Sloan Digital Sky Survey had captured the same body just one week before this official discovery.

Who is the Japanese rocket scientist honored by the name 25143 Itokawa?

The Minor Planet Center officially published the name 25143 Itokawa on the 6th of August 2003 to honor Hideo Itokawa who lived from 1912 to 1999. He is widely regarded as the father of Japanese rocketry.

What are the orbital characteristics of 25143 Itokawa?

Itokawa orbits the Sun at a distance ranging from 0.95 to 1.70 AU every 18 months with an orbital period lasting exactly 557 days. The path has an eccentricity of 0.28 and an inclination of 2 degrees relative to the ecliptic.

When did the Hayabusa spacecraft return samples from 25143 Itokawa to Earth?

The sample capsule returned to Earth and landed at Woomera, South Australia on the 13th of June 2010 around 13:51 UTC. Japan Aerospace Exploration Agency confirmed dust from the voyage originated from the asteroid on the 16th of November 2010.

How was the physical structure of 25143 Itokawa determined by scientists?

Radar imaging by Goldstone in 2001 observed an ellipsoid shape measuring approximately 540 meters long and 290 meters wide. Scientists concluded that 25143 Itokawa is not a monolith but rather a rubble pile formed from fragments that have cohered over time due to its low density.

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All sources

38 references cited across the entry

  1. 1webConfirmed: Hayabusa Nabbed Asteroid ParticlesNancy Atkinson — Universe Today — 16 November 2010
  2. 2newsItowaka Geological Map
  3. 3newsLocal site names on Itowaka
  4. 4newsThe Anatomy of an Asteroid
  5. 5newsHayabusa: Itokawa Beckons as Japan's Spacecraft Searches for Places to Touch Down
  6. 6newsAsteroid Dust Confirms Meteorite Origins25 August 2011
  7. 7newsMost Earth meteorites linked to single asteroid26 August 2011
  8. 8journalThe origin of hydrogen in space weathered rims of Itokawa regolith particlesL Daly et al. — 2018
  9. 9journalEstablishing Itokawa's water contribution to EarthJin Z et al. — 2018
  10. 10conferenceFirst Identification of Indigenous Organic Matter Alongside Water In Itokawa Particle Returned By The Hayabusa MissionQ Chan et al. — 2020
  11. 11journalSolar wind contributions to Earth's oceansLuke Daly et al. — December 2021
  12. 12webUp to half of Earth's water may come from solar wind and space dustLuke Daly et al. — November 30, 2021
  13. 13webEros's puzzling surface
  14. 14webJPL Small-Body Database Browser: 25143 Itokawa (1998 SF36)Jet Propulsion Laboratory
  15. 15bookDictionary of Minor Planet Names – (25143) Itokawa, Addendum to Fifth Edition: 2003–2005Lutz D. Schmadel — Springer Berlin Heidelberg — 2006
  16. 16web25143 Itokawa (1998 SF36)
  17. 17webMPC/MPO/MPS Archive
  18. 18webOfficial Approval of Names on Itokawa by IAU3 March 2009
  19. 19webPlanetary Names: Itokawa
  20. 21journalRadar Observations of Asteroid 25143 (1998 SF36)S. J. Ostro et al. — November 2001
  21. 22journalItokawa Dust Particles: A Direct Link Between S-Type Asteroids and Ordinary ChondritesTomoki Nakamura et al. — August 2011
  22. 23journalThe Rubble-Pile Asteroid Itokawa as Observed by HayabusaA. Fujiwara et al. — June 2006
  23. 24journalMass and Local Topography Measurements of Itokawa by HayabusaShinsuke Abe et al. — June 2006
  24. 25conferenceNew Clues to Ancient Water on ItokawaZ. L. Jin et al. — March 2018
  25. 26journalSpectral properties of near-Earth and Mars-crossing asteroids using Sloan photometryB. Carry et al. — April 2016
  26. 27journalPhysical characterization of Warm Spitzer-observed near-Earth objectsCristina A. Thomas et al. — January 2014
  27. 28journalCCD photometry and model of MUSES-C target (25143) 1998 SF36M. Kaasalainen et al. — July 2003
  28. 29journalThermal observations of MUSES-C mission target (25143) 1998 SF36T. Sekiguchi et al. — January 2003
  29. 30journalExploreNEOs. III. Physical Characterization of 65 Potential Spacecraft Target AsteroidsMichael Mueller et al. — April 2011
  30. 31journalRotational Studies of MUSES-C Target Asteroid (25143) 1998 SF36J. S. Lambert et al. — December 2001
  31. 32journalCCD Observations of Asteroid 1998 SF36 (25143)S. C. Lowry et al. — November 2001
  32. 33journalCCD Photometry of the MUSES-C Mission Target: Asteroid (25143) 1998 SF36Budi Dermawan et al. — August 2002
  33. 34journalPole orientation and triaxial ellipsoid shape of (25143) 1998 SF36, a target asteroid of the MUSES-C* missionY. Ohba et al. — June 2003
  34. 35journalLightcurve analysis for numbered asteroids 301, 380, 2867, 8373, 25143, and 31368Warner, Brian D. — September 2004
  35. 36journalPhysical properties of Asteroid (25143) Itokawa – Target of the Hayabusa sample return missionStephen C. Lowry et al. — August 2005
  36. 37journalGround-based Lightcurve Observation of (25143) Itokawa, 2001–2004S. Nishihara et al. — March 2005
  37. 38journalNew photometric observations of asteroids (1862) Apollo and (25143) Itokawa – an analysis of YORP effectJ. Durech et al. — September 2008
  38. 39journalExploreNEOs. V. Average Albedo by Taxonomic Complex in the Near-Earth Asteroid PopulationC. A. Thomas et al. — September 2011